An overview of sexual selection in the cricket species Teleogryllus oceanicus and research procedures

Rapid evolution of a sexual signal in the field cricket, Teleogryllus oceanicus

The dulcet tones of cricket song that we find so relaxing on warm evenings are actuallythe advertisement calls of sexually receptive males. A nasty threat looms overTeleogryllus oceanicus populations in Hawaii, however. A villain of the blackest dye, theparasitoid fly Ormia ochracea, emerges at night to prey on hapless male crickets. Femaleflies hone in on male cricket song, and squirt live larvae onto their hosts. Larvae thenburrow through the cuticle and feast on various internal cricket structures. After a weekor so, the engorged, pulsing maggots burst out of their host, leaving a hollow crickethusk behind. Clearly, this is not a desirable situation to be in if you are a malecricket. Our research team has recently made an astonishing discovery on the Hawaiianisland of Kauai.

In 2003, an eerie silence had descended on the population. Had all the males ceased calling? Had the population gone extinct? After some investigation, we discovered that a dramatic morphological mutation had arisen in some males, causing the loss of sound-producing structures on their wings (larger image). These flatwing males are protected from predation by acoustically orienting parasitoids. The proportion of flatwing males on Kauai has increased from zero to nearly 90 percent in fewer than 30 generations, representing one of the fastest evolutionary shifts documented in a wild population. We are currently investigating the extent to which pre-existing behaviors facilitated the emergence and spread of this mutation, providing new and exciting insights into the interactions between behavior and evolutionary change.

Our work on this system now features in the most recent edition of "Principles of AnimalBehavior" by LA Dugatkin. For further reading, check out:

In many animal species, females have more robust immunity and are less likely to harborparasites than males. Why is that? Comparative and theoretical work from current andformer lab members has examined the evolutionary causes of sex-biased parasitism andimmune responses, placing these traits in the context of sexual selection. Check out:

Those of us who study sexual behavior in animals have noticed that people like to applywhat we learn to their own behavior. We often get people asking questions like, "Ismonogamy natural?" or "Does homosexuality exist in non-humans?" Marlene Zuk and others inthe lab enjoy interacting with other scientists as well as the general public indiscussions of these and related issues, and if you are interested, you can check out someof the following: